Fears are growing across South East Asia about the health risks of toxic smoke from burning farmland and forests in Indonesia.

A smoky haze is spreading across the region from hundreds of separate fires in Sumatra and Borneo, mainly caused by farmers clearing land in preparation for the planting season.

Officials say smog has reduced visibility and led to an increase in eye complaints and breathing difficulties.

Southern Thailand and Malaysia are also affected - the authorities in Malaysia have banned the burning of rubbish in open fires.

Smog can cause serious health problems

In southern Thailand, residents of five provinces have been warned to stay indoors or wear face masks to ward off the effects of smoke blown in from the Indonesian island of Sumatra.

So far, the problem is not as serious as four years ago, when a thick smog covered much of the region, although meteorologists warn that the situation could deteriorate in the coming dry season, which may be longer than usual.

Health problems

Our correspondent in Jakata, Simon Ingram, reports since the weekend, people living in West Kalimantan, in Indonesian Borneo, have woken to find the streets blanketed in a thick, choking haze.

Early morning flights into the provincial capital, Pontianak, have been delayed due to low visibility, and boat traffic on the Kapuas river has been affected too.

The smoke is apparently caused by farmers burning off grass and vegetation on the land where they will soon be planting another rice crop.

Hundreds of fires are reportedly burning in Indonesia

It is not clear how much is caused by companies illegally clearing forest to make way for more palm oil plantations.

Such commercial operations were widely blamed for producing the environmental crisis of 1997, when thousands of fires raged out of control for months, spreading a dense toxic cloud of air pollution across much of the region

The situation was made worse by abnormally dry weather conditions created by the El Nino phenomenon.